The present invention relates to fluid-driven reciprocating pumps. The invention is particularly applicable to the reciprocating pump illustrated in our U.S. Pat. No. 4,021,149 for use in injecting fertilizer into a water supply line, and is therefore described below with respect to this application.
The pump illustrated in the above-cited Patent has limited injection capacity, and moreover, can inject only one fertilizer solution. There are many applications requiring a larger injection capacity than capable of being attained by the pump of that Patent, and other applications requiring the injection of two different fertilizer solutions that cannot be mixed in one tank because they tend to precipitate but rather can be mixed only when injected into the water supply line where the precipitation problem is not present because of dilution by the water in the supply line.